1. Field of the Invention
The present invention relates to a process for producing a liquid jet recording head which is used in a liquid jet recording system by depositing printing liquid droplets on a printing medium. More particularly, the present invention relates to a process for producing a so-called side-shooter type liquid jet recording head which discharges printing liquid droplets (or ink droplets) in a direction perpendicular to its substrate containing a liquid discharge pressure generating element installed therein. The present invention includes a side-shooter type liquid jet recording head produced by said process.
2. Related Background Art
Japanese Unexamined Patent Publication No. 234941/1987 discloses a typical process of producing a side-shooter type liquid jet recording head by joining an orifice plate produced by way of electroforming to a substrate having an ink discharge pressure generating element formed therein through a patterned dry film. FIG. 3(a) is a schematic cross-sectional view illustrating an example of a side-shooter type liquid jet recording head produced by said process. Particularly, the liquid jet recording head shown in FIG. 3(a) comprises a substrate 11 having an ink discharge pressure generating element 12 therein which is joined to an orifice plate 15 through a dry film 18 to form a liquid pathway. Reference numeral 16 indicates an ink discharge outlet provided above the ink discharge pressure generating element 12. Reference numeral 17 indicates a bubbling chamber provided at a portion where the liquid pathway is communicated with the ink discharge outlet 16. The substrate 11 including the ink discharge pressure generating element 12 constitutes a bottom wall of the bubbling chamber 17. The bubbling chamber 17 retains ink therein. When the ink discharge pressure generating element 12 comprises an electrothermal converting element (or a heat generating resistor), a thermal energy is applied to the ink in the bubbling chamber 17 by the electrothermal converting body to cause a state change in the ink, where a bubble is generated in the ink and the pressure which occurs upon the generation of the bubble makes the ink in the bubbling chamber 17 discharge through the discharge outlet 16.
Now, in this liquid jet recording head, there is an occasion where an undesired air bubble is contaminated into the liquid pathway. This occurs mainly because when the temperature of the ink is changed, air dissolved in the ink is vaporized to form such air bubble in the ink or because external air is contaminated into the liquid pathway during the supply of the ink to form such air bubble in the liquid pathway. In the case where the amount of the air bubble is slight, it is emitted outside the head together with the ink discharged. However, in the case where the air bubble remains while being adhered on the circumferential wall or the like of the liquid pathway, the air bubble is liable to grow, resulting in imparting a negative influence to the ink discharging performance. Particularly, when the air bubble is grown and contaminated into the bubbling chamber, the grown air bubble present in the bubbling chamber is liable to entail a problem in that it absorbs the pressure used for discharging ink from the discharge outlet, so the ink is discharged from the discharge outlet in a defective state.
More particularly, the bubbling chamber 17 of the liquid jet recording head has corner portions (20) on the discharge outlet side, where the flow of ink is likely to stagnate at the corner portions. When the foregoing contaminating air bubble should enter into the corner portions 20 as shown in FIG. 3(a), the contaminating air bubble stays therein to grow, whereby entailing problems such that the frequency of ink to be refilled is decreased and the direction for an ink droplet to be flying is deviated, resulting in causing dislocation for the ink droplet deposited on a recording medium and making the ink discharging performance unstable. Further, when the contaminating air bubble staying in the corner portions should be greatly grown, the ink discharging performance is sometimes disabled.
Japanese Unexamined Patent Publications Nos. 10940/1992 and 10941/1992 disclose a side-shooter type liquid jet recording head having the configuration as shown in FIG. 3(b) in which no dry film is used, which comprises a substrate 11 having a heat generating resistor 12 (or a ink discharge pressure generating element) and an orifice plate 15 joined to said substrate to form a liquid pathway. The liquid jet recording head shown in FIG. 3(b) is provided with an ink discharge outlet 16 situated above the heat generating resistor 12 and a bubbling chamber 17 in communication with the discharge outlet 16. The substrate 11 including the ink heat generating resistor 12 constitutes a bottom wall of the bubbling chamber 17. The bubbling chamber 17 retains ink therein. In the liquid jet recording head shown in FIG. 3(b), thermal energy is applied to the ink in the bubbling chamber 17 by the heat generating resistor 12 to cause a state change in the ink whereby generating a bubble in the ink, where the bubble generated is communicated with outside air to make the ink in the bubbling chamber 17 discharge through the discharge outlet 16.
In the liquid jet recording head shown in FIG. 3(b), outside air eventually enters into the bubbling chamber 17 and because of this, an air bubble often remains in the bubbling chamber 17 without being emitted to the outside. When said air bubble is adhered at corner portions 20 of the bubbling chamber 17, a discharged volume itself is varied to make the resulting print to be accompanied by unevenness or stripes. When the air bubble stays in the corner portions 20, as well as in the case shown in FIG. 3(a), there are problems in that the frequency of ink to be refilled is decreased and the direction for an ink droplet to be flying is deviated, resulting in causing dislocation for the ink droplet deposited on a recording medium and making the ink discharging performance unstable. Further, when the ink in the corner portions 20 does not flow, residual ink causes problem of making the ink discharging performance unstable.
The above-described problems will become significant as the size of an ink droplet to be discharged is diminished so as to comply with the conditions for obtaining a highly precise fine image.
Hence, any of the conventional side-shooter type liquid jet recording heads is problematic in that the corner portions present at the upper position of the bubbling chamber entail such negative influences as above described to the ink discharging performance. In the prior art, there cannot be found an adequate manner for effectively producing a desirable side-shooter type liquid jet recording head with no corner portion in the bubbling chamber.